Electric call or signal apparatus



(No Model.)

G. W. FOSTER.

ELECTRIC CALL OR SIGNAL APPARATUS.

No. 371,752. Patented Oct. 18,1887.

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A r-romvn N. PETERS. FYIMOUUIOBHP'NJV. Washington. D. C.

' TINTTED STATES PATENT Urrrcs.

' GEORGE w. FOSTER, or GALVESTON, TEXAS.

ELECTRIC CALL OR SIGNAL APPARATUS.

SPECIFICATION forming part of Letters Patent No. 371,752, dated October 18, 1887.

Application filed January 13, 1887. Serial No. 224,199. (No model.)

To all whom it may concern:

Be it known that I, GEORGE W. FOSTER, a citizen of the United States, residing in Gal- :veston, in the county of Galveston and State of Texas, have invented certain new and useful Improvements in Electric Call or Signaling Apparatus; and I do hereby declare that the following is a full, clear, and exact description of my invention, such as will enable others skilled in the art to which it appertains to make and use the'same.

My invention consists, broadly, in provid ing means whereby a polarized electric bell capable of being operated rapidly by currents of alternating polarity may also be operated by constant currents of the proper polarity.

It is my design to apply my invention especially to the ordinary magneto-bells employed in calling subscribers in telephone systems. In adapting it to such use I generally prefer to make the connections and adjustments such that the currents of constant po larity will cause the bell-armature-to be actuated slightly, but not with sufficient force to cause the subscribers bells to ring. The object .of such a construction is to furnish means for testing at any time the condition of a given circuit by means of apparatus located at a central office or station. In such cases the battery which furnishes the constant current has in its circuit a telephone which is connected up between the battery and a switch or plug for making the line-connection, the battery and telephone both being located at the central office. By turning the switch or inserting the plug and listening at the telephone an operator can determine whether the line is complete or not, according as he hears or fails to hear a buzzing sound, caused by the vibrations of the. bellarmature at the subscribers station. Thus the application of my invention to telephone-lines furnishes a very convenient means for testing such lines. Between the telephone and the battery a manual pole-changer is located, by means of which the polarity of the current sent through the telephone to line may be changed at will.

On lines where there are two subscribers my apparatus can be used to serve the purposes of an individual call apparatus-that is to say, one of the bells may be so connected and adjusted as to be operated by a constant positive and the other bya constant negative current, while both bells may be set in operation by the usual magneto-currents in case it should be desirable for any reason to call up both subscribers at once.

By using suitable relays in a manner well understood my devices can be applied to calling individuals on circuits including more than two subscribers stations. The devices by means of whichthe ordinary magneto-bells can be adapted to the functions above set forth are very simple and involve very little increase in the cost of each bell.

My devices can be applied to any of the bells now used without altering in any essential manner their construction or adjustment.

I have illustrated my invention in the accompanying drawings, in which- .Figure 1 represents an elevation of my signaling apparatus and a diagram of the circuits. up in the same circuit, and Fig. ,3 is a detail view.

Referring to the drawings by letter, M M is an electro-magnet having polarized cores m m. The magnet is provided with a neutral armature, A, with which a bell-hammer, K, is connected.

C is agong or bell on which the hammer acts. The gong and the magnet are supported upon a suitable frame, D.

Near one end of the armature A is supported a post, E, which forms one terminal of an electric circuit, as will appear hereinafter. Above the said terminal, on a suitable block or support, A, is located a corresponding terminal post, E. The latter terminal is screwthreaded, so as to be adjustable with respect to the former. Another screw-post, S, passes into the block A, and bears against the upper end of a spring, S, which presses at its lower end against the armature A. The latter is centrally pivoted to a yoke, F, which is held by a screw, f, within a notch in the block A.

The magnet M M is connected up in amainline circuit G G, and is so wound that a current of one polarity will increase the attraction of one of its poles and decrease that of the other, while a current of opposite polarity will increase the attraction of the second and decrease that of the first pole. Magnets of this class are common, and the details of con Fig. 2 shows two of my bells connected struction do not need to be set forth further. It is obvious that with such a magnet alternating currents on line-such as are furnished by the ordinary magneto-call apparatus-will cause the armature A to vibrate and the bell G to be sounded. Now, I run a wire, B, from one side of the magnet M M to the terminal E, and a wire, B, from the other side of the to the armature A at the right of its pivot, if

I send a negative current to line, its only effect will be to assist the spring S in keeping the right-hand end of the armature down. If, however, I send a positive current to line, the left-hand end of the armature will be drawn down against the force of the spring S.. This will cause contact to be made between the terminals E E, and produce a short circuit of very low resistance around the magnet, as already described. By reason of the short circuit the greater part of the current will be cut off from the magnet, and its armature will bereleased; but this action willin turn break the short circuit and restore the magnet-circuit, after which the described action will be repeated. Thus it appears that my bell may be operated either by a magneto-current or by a current of constant polarity.

It is of course understood that my bell may be so adjusted and connected as to respond to a constant :current. of negative polarity, instead of to one of positive polarity. By making the spring S very light and adjusting the terminals so that the short circuit will not be closed until the movement of the armature toward the operating-pole is about completed the apparatus may be made to sound the bell in response to a magneto-current, and to cause avibration of the armature without operating the bell in response to a constant current of the right polarity.

In Fig. 2 I have shown two bells capable of being operated by currents of opposite polarity. The general construction of the bells is identical with that detailed above, except that the spring S will generally be made somewhat stronger and the adjustment of the terminals will be altered. The object is to adapt my apparatus to the purposes of an individual-call apparatus. It is clear that a current of either polarity will operate but one of the bells, so that either of two subscribers on the line can be called without calling the other.

At theleft of the drawings isshown aswitch, H, battery I, and a telephone, T, in circuit with the battery. By turning the switch into contact with one or the other of the contactv pieces 72. h the battery I will be connected passes through the two bells illustrated in Fig. 2. Between thebattery and the telephone is located a manual pole-changer, W, which consists of two pivoted metallic arms, to w, connected by a non-metallic insulating-arm, V, having a handle, 12. The free ends of the arms w and 10 may be broughtinto contactln an obvious manner either with the contactpieces 00 and 3 or g and 2:. Now, the plate 3 is connected to ground. It is obvious, therefore, that by turning the pole-changer to its two positions a different pole of the battery will be grounded and a current of different polarity will be sent to line in each instance.

Suppose, now, that the pole-changeris so turned as to send a current of the proper polarity to line, and suppose, also, that the switch H has been brought into contact with the contactplece h, a vibration of the armature A in Fig. 1 will be caused, and an operator listeningat the'telephone can easily test the condition of the circuit. If the operator fails to hear the well-known buzzing sound, it will indicate that the circuit is incomplete, and measures can at once be taken to restore it.

If the switch H be turned to the contactpiece it, one or the other of the bells in Fig. 2 will be operated, the particular one being determined by the position of the pole-changer W. A current of either polarity, however, will be sufficient to serve the purpose of testing the line in this instance.

The condition of the parts necessary to make my bell perform the above function does not interfere in the slightest with its use in ordinary magneto-signaling.

In Fig. 2 the spring S and the various adjustments may remain substantially the same as in Fig. 1, in which case the apparatus might be used to test the line, to call either subscriber to the exclusion of the other, or to call both subscribers through the magneto apparatus.

Instead of short-circuiting the whole magnet M M, I may short-circuit only one of its coils by the contact of the terminals E E. Moreover, the details of the device supported on the block A and of the block itself may be altered without departing, essentially, from the principle of my invention.

The switch H may be replaced by the ordinary switch or connecting-plug, and the contact-pieces h h by the bars of a telephone switchboard-that is, anything which serves as a means for connecting the battery and telephone with the main line may be considered as equivalent to the switch H and its connected parts.

It will be observed that my bell is like the ordinary magneto-bell, with the addition'of the very few and inexpensive parts included IIO in the short circuit and connected with the The form of the parts will of course be altered to suit different kinds of magneto-bells to which it maybe applied. It is obvious that the terminals E and E may be brought into contact by an attachment or extension of the armature, as well as by the armature directly.

It will be observed that whenever a batterycurrent is employed to operate one of my bells it actuates the same by variations in the strength of the current which passes through the magnet and not by an alternate passing and interruption of the current-that is to say, contact between the terminals E and E simply closes a short circuit around the mag net M M, while the breaking of contact between those parts restores the circuit through the magnet. At no time, however, is the circuit broken. This being the case, it is obvious-that the sound in the telephone, which constitutes the return-signal, is caused by an increase and diminution of the battery-current on line, and not by an interrupted current.

' '1 represents an ordinary magneto-call apparatus, by means of which both bells in the lower circuit may be rung or the single bell in the upper circuit, according to the position of the switch H.

Having now described my invention, whatI claim is 1. A polarized electro-magnet and a short circuit around the same, which is closed when the magnet is traversed by a constant current of a given polarity, in combination with a galvanic battery and a magneto-generator, both in circuit with the said electro-magnet,as set forth.

2. A pair of polarized electric bells, each having a short circuit which is closed when the bell-magnet is traversed bya constant current of differentpolarity, in combination with a galvanic battery and a magnetogenerator, both in circuit with said bells, as set forth.

3. In a telegraph or telephone circuit, the combination, with a polarized electro-magnet and a short circuit around the same, which is cnoaen w. nosrnn.

Witnesses:

E. STARENHAGEN, E. J. Konnre. 

